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New research shows a major section of west Antarctica's ice sheet will completely melt in coming centuries and probably raise sea levels higher than previously predicted, revealing another impact from the world's changing climate. According to a study released Monday, warm ocean currents and geographic peculiarities have helped kick off a chain reaction at the Amundsen Sea-area glaciers, melting them faster than previously realized and pushing them "past the point of no return," NASA glaciologist Eric Rignot told reporters.

The glacial retreat there "appears unstoppable," said Rignot, lead author of a joint NASA-University of California Irvine paper that used 40 years of satellite data and aircraft studies. NASA says the region has enough ice to raise global sea levels by 4 feet. According to Rignot, conservative estimates indicate the complete melting of the Antarctic ice cited in the study could take several centuries. However, the melting could have an impact this century, according to Sridhar Anandakrishnan, a geosciences professor at Pennsylvania State University.

The United Nations' most recent climate change report estimated sea levels could rise from about 1 foot to 3 feet by 2100. Such a rise could displace tens of millions of people from coastal areas around the world.